Method of cracking and processing petroleum hydrocarbons



J. C. BLACK Nov. 25, 1930.

METHOD OF CRACKING AND PROCESSING PETROLEUM HYDROCARBONS Original FiledMay 17 2W e.. MLM -N` Patented Nov. 25, 1930 UNITED 'STATES PATENTOFI-icaA JOHN C. BLACK, OF WILMINGTON, CALIFORNIA, ASSIGNOR, BY MESNEASSIGNMENTS,

T0 GASOLINE PRODUCTS COMPANY, INC., OF WILMINGTON, DELAWARE, A COR-PORATION 0F DELAWARE METHOD 0F CRACKING AND PROCESSING- PETROLEUMHYDROCARBONS Application led May 17, 1924, Serial This invention relatesto certain new and useful improvements in petroleum hydrocarbon crackingand more particularly to my petroleum hydrocarbon cracking processes,Patents Nos. 1,426,813 and 1,456,419, also to my application No.602,439, and this application is a continuation in part of the abovepatents and application.

In my application No. 602,439 I describe a method of introducing freshsupply oil into the cracking or converging system by having -a separateheater for the preliminary heating of the fresh oil or make-up oil andintroducing it into the carbon precipitating chamber or direct intoanexpansion drum-from whence it goes into the fractionating tower. By mynew method, I do not use a separate heater setting but use a heating-coil which I have denominated an economizer coil and which I set in theterminal combustion space of the main furnace, the coil in that positionabsorbing` suicient heat to obtain satisfactory results. Furthermore, bymy new arrangement of apparatus, I am enabled to nass cycle stockthrough the economizer coil; this stock is the same as that passingthrough the main cracking coils and may be drawn from the same source ofsupply. I am also able to introduce new make-up oil through theeconomizer coil and discharge it either into the mixing chamber underpressure or into the header connecting with `the fractionating tower, asdescribed in my application No. 602,439.

In the apparatus disclosed in this application the main heating andcracking coils, together with the carbon precipitatlng chamber ordigester and the means for operating under pressure are the same asdescribed in my Patents Nos. 1,426,813 and 1,456,419, so that if I amintroducing-the economizer oil into the carbon precipitating chamber ordigester, as the case may be, it will be under such pressure as toovercome the pressure prevailing in the mixing chamber which is such asto materially prevent vaporization of the cracked oils therein, that issubstantially in a liquid phase whereas if I discharge the economizeroil into the header or fractionating tower direct, I will not becompelled to No. 714,070. Renewed April 17, 1930.

carry such a high pressure, for the reason that the temperature of theoil in the economizer coil is lower than that in the main cracking coil,and, therefore, its vapor pressure is less, but I carry sufficientpressure on the economizer coil at all times to prevent materialvaporization irrespective of the manner of discharge.

My preferred method of operating is to so regulatel the quantity of oilpassing through the economizer coil as to bring its temperature to a'degree of heat approximating its incipient cracking point or preferablyto a point below its carbonizing point,

in order to prevent fouling of the tubes of the economizer coil. Thedesired temperature will usually be between six and seven hundreddegrees Fahrenheit for most oil but it can be operated at a highertemperature if desired or even lower one, but I prefer to operate at atemperature of six hundred to seven "hundred degrees Fahrenheit. Whenthis temperature is attained, the oil is injected into the mixingchamber, wlierein it intermingles with the highly heated oil coming fromthe main heating or cracking coils, whereby its temperature is suddenlyincreased to an exceedingly active cracking` temperature, the pressurebeing maintained in the mixing chamber sufficient to prevent materialvaporization therein, from whence the mixture of oils passes to the heatexchanger, if one is employed, and then to the presure reducing anddischarge valve. The oil pumped through the economizer coil is eitherfresh make-up oil or cycle stock 0btained from the supply coincidentlypumped through the main lheating or cracking coils. This 1s my preferredmethod of operating rather than to discharge the economizer oil directto the fractionating tower, although this may be found desirable attimes and the apparatus is so constructed as to permit of operating inthat manner.

The exceptional results obtained by the introduction of economizer oilinto the highly heated cracked oil present in the mixing chamber is due,I believe, to the exceedingly is practically instantaneous in itsrapidity,

and is of such degree as to constitute an explosive shock to themolecules of the hydrocarbons, especially in view of the fact that thepressure maintained on the hydrocarbons is suHicient to prevent anymaterial vaporization with its resultant cooling effect, thereby holdingthe oils in a liquid Contact at the active cracking temperature due totheir mixture; as for instance, if the econoniizer oil enters the mixingchamber at 700o Fahrenheit and the ingoing primarily cracked oil is 900oFahrenheit and the ratio of economizer oil to the primary oil is as oneis to two, then the resultant temperature of the mixture is 830OFahrenheit and the instantaneous rise of temperature of the economizeroil will be 130O Fahrenheit and which it will attain in a fraction of asecond, whereas if it was heated in a coil to a corresponding degree, itwould require several minutes to attain such increase. In other words,the heating time element is probably two to three hundred times as fastby direct admixture as by extraneous heating and it is this rapidheating of almost explosive violence that produces the breakdown of themolecular structure and causes cracking. I cannot otherwise account forthe results obtained by this method as against slower heating, as theyield of gasoline may equal or even exceed the amount obtained in theprimary crac-king operation wherein the temperature may be 75 to 100DFahrenheit higher, the same oil being used in both circuits.

Another object of my invention is the improved operating condition whichis brought about by the introduction of the secondary supply of oil intothe primary supply. It seems to have a marked influence on the characterof the carbon formation by creating a condition whereby the carbon isprecipitated in a more finely divided state and which is less coherentand is more easily cleaned out of the chamber, and by this improvedcondition thus created, I am enabled to operate for a much longer timewithout shutting down for carbon removal; heretofore, the running timewas largely dependent upon the accumulation of carbon at the point ofexit from the chamber, this accumulation gradually building up adifferential pressure between the inlet and outlet pressures to a pointthat was impractical to further operate at and cleaning was necessary.By my new arrangement, the practical running time is increased to a verygreat extent and which I have found to be four to five times as long andin some cases even more. This, however, is largely dependent upon thecharacter of the oil being used in the secondary coil.

The setting of the main furnace may be such that an auxiliary fire maybe used to give additional heat to the economizer coil and, under somecircumstances, this may be desirable. In my drawing of the apparatus, Ishow the auxiliary firing or combustion chamber but it is to beunderstood that this may be dispensed with and good results obtainedthereby. I also show in the drawing a heat exchanger apparatus designedto extract heat from the outgoing cracked or converted oil and exchangeit to the ingoing oil to be cracked. This may be dispensed with but itis a heat economizer and I show it as a part of the apparatus but it isnot an essential part thereof.

I also show a preheater coil situated in the hottest portion of thefurnace to act as a protector and absorber of radiant heat and excessiveheat that would otherwise impinge upon the final or terminal heatingcoils. This coil and its function s described in my copendingapplication No. 712,156 filed May 9, 1924.

I am also showing fractionating towers wherein the vapors arefractionated and separated into their various products.

I am showing all this apparatus so that anyone familiar with the art towhich this invention relates may be enabled to construct and operate thecomplete plant.

As before mentioned, I may use an auxiliary fire or supply of heat toobtain closer regulation of the heating in the economizer coil and alsoto increase the quantity that may be heated; this also enables me tosecure a somewhat higher heat in the oil or hydrocarbons passing throughthe economizer coil and thereby increase the final cracking effeet.

A heat interchanger may also be employed to preheat the ingoing oil tothe economizer coil and extract heat from the outgoing oil, therebyincreasing the heating effect in the economizer coil.

The carbon precipitating or mixing chamber will act to catch any freecarbon which can be periodically removed by blowing down as described inmy Patent No. 1,456,419, or it may be removed by disengaging the endclean-out closures and removing the carbon or carbonaceous material byhand or otherwise.

By the above described method of operation, the mixing chamber becomes aheating element by the fact that the ingoing oil is of highertemperature from the main cracking coil than that entering from theeconomizer coil and heat is imparted to the latter.

In my Patent No. 1,426,813, I describe a reaction chamber or digesterwherein the cracking reaction is continued outside of the heating coilsand it is to be understood that the application of the economizer coilto that type of apparatus is feasible and practical and by theintroduction of oil from the economizer coil into' the reaction chamberor digester will bring about an increased yield with to any appreciableextent.

The mixing chamber and its connections p may be so arranged as to createa gas space in the upper portion of the chamber, where gases andpossibly some vapors that are generated by the process may accumulate.These gases or vapors will, of course, be under the pressure maintainedin that portion of the apparatus and will-actas a cushion or shockabsorber on the pumping system and will have a tendency to smooth theaction of the pump and relieve any undue hydrostatic pressure on thetubes, gauges, valves, and other parts of the apparatus.

In the yheating and cracking furnace, as depicted in the accompanyingdrawing, the primary cracking operation is accomplished in the coilssubstantiall as described in my Patent No. 1,456,419. n this case, theinjection oil from the economizer coil is introduced into the mixingchamber at a coincident point with the main portion of cracked oilentering from the primary cracking coils.

The apparatus is so arranged in regard to tanks, pumps, lines, coolers,condensers, etc., that the oil or hydrocarbons circulated through theeconomizer coil can be either a virgin make-up oil or it may be derivedfrom the heav or high-boiling point fractions separatedl in thefractionating apparatus. There is also arrangement made for bypassingthe economizer oil from entering the carbon precipitating or mixingchamber and passing it directly to the vaporizin and fractionatingtower. This may be deslrable at times either for control or forintroducing stocks into the cracking system. I have fou'nd that when aheavy fuel oil or crude oil or in fact any oil which on normaldistillationl (that is not destructive distillation) will produceviscous residues or fractions, if introduced into the cracking systemthrough the economizer coil and heated to a degree approximating itscracking point, then discharging it into the carbon precipitating ormixing chamber or into a digester Lor reaction chamber, that the heavyviscous fractions contained therein are cracked and renderedcomparatively non-viscous so that the residues or heavy fractionsobtained by this method of operating are easily pumped or otherwise-disposed of.

In this system I prefer to use a separate pump for each oil circuit-onefor the economizer circuit and one for the main cracking circuit, forseveral reasons: First, different stocks may be used in the two circuitsand, second, better control may be obtained. It is quite practical,however, to use one large pump to feed all the economizer coils and haveseparate pumps for each main cracking unit where several such units arein a battery; likewise, a large pump may be employed to feed all themaincracking coils but I prefer separate pumps on each cracking unit.This, however, is immaterial to the process but is here-mentioned toguide anyone who may wish to construct an apparatus embodying thisinvention.

Referring to the drawing: Figure 1 represents the complete apparatus inpart section and part elevation, and Figure y2 represents the crackingfurnace in section at right angles to that shown in Figure 1. Figure 2shows the mixin chamber in its correct p0- sition, whereas in igure 1,it is shown below the furnace and is so depicted for clearness andsimplicity; the balance of the apparatus is so disposed in the drawingas to show the relation of one part to another and is not meant to showthe actual position of the various parts. Similar numbers in Figure 1and Figure 2 represent like parts.

In the drawing l represents the furnace; 2 the preheater coil; 3 thepipe connection from the preheater coil to the intermediate coil 4, and5 the connection from the intermediate coil 4 to the final or crackingcoils 6; 7 is a pipe connection from the final coils to the carbonprecipitating or mixing chamber 8; 9 is a blow down connection; 10 is adischarge connection from the carbon precipitating or mixing chamber tothe heat exchanger 11; '12 is a connection from the heater exchanger toa bypass trap 13; 14 is a connection and 14 is a pressure reducing valvetherein connecting the bypass trap 13 with the discharge header 15,which in turn is connected into the fractionating tower 16, which isdivided in various sections 17, 18 and 19; 20 is a vapor pipe connectingthe tower 16 into the fractionating tower 21; 22 and 23 are boilingdecks for fractionating the vapors and condensates; 24 is an analyzer orrefluxing condenser; 25 is a vapor line connecting the tower 21 with thecondenser; 25 is a valve in the vapor line 25; the condenser connectsvwith the look box 26 and through pipe 27 to the light naphtha tank; fromthe outlet end of the condenser there is also a connection 28 which actsas a gas vent connected to a gas header not numbered. Tower 21 is fittedwith a draw-off arrangement 29 connecting with a cooler which in turnconnects to the supply tank and heavy naphtha tank through look box 30and lines 31 and 32. Compartment 17 is connected by pipe 33 and valve 33to the residue tank; compartments 18 and 19 are fitted with draw-offpipes 34 and 35 respectively and are fitted with valves 34 and 35 and acrossover connection and valve 36 between the lines 34 and 35; lines 34and 35 are connected to the cooler; from the cooler are look boxes andconnections 37 and 38 connecting to the supply tank and the intermediatenaphtha tank respectively. The tower compartments are fitted with spraydevices 39 and 40, connected by pipe connections 41 and 42, controlledrespectively by valves 41 and 42, and thence by` pipe 43 to the pump 44.There is a connection 45 and valve 45 leading from pipe 43 andconnecting with the analyzer 24. There is also a connection 46 from theanalyzer controlled by valve 46 and connecting with the pipe 35 leadingto the cooler. There are connections 47 and 48 connecting with pipes 35and 46, respectively, which connect with the fractionating tower 21. Thebypass trap 13 is inserted in water or water jacket 49 and is fittedwith a blow-off connection 50; from a point above the bottom aconnection 51 is made to the cooler 52 and through line 53 it connectsto the control board 54 on which are mounted the control valves andpressure gauges. On the control board the line 53 is fitted with aterminal pressure gauge 55 and a pressure reducing valve 55', fromwhence it connects to two tanks, one for slop oil and one for crackedoil, through the line 56 which is fitted with branch lines and valvesconnecting with each tank. The pump 44 takes suction through line 57 tothe intermediate naphtha tank and also the heavy Ynaphtha tank throughbranch connections and valves to each tank.

Pump 58v takes suction through line 59 with the water tank, the sloptank and the supply tank through branch pipes and valves to each tank;pump 58 discharges through line 60 to the control board 54 whereon aremounted a pressure control valve 61 and a pressure gauge 62 in line 60which extends to and is connected into the preheater coil 2; betweenlines 56 and 60 is a bypass valve and connection 63. The pump 64 has asuction connection through line 65 and valve 65 to the fresh oil supplytank 84; it also has a branch suction line 66 and valve 66 connecting tothe supply tank 83; pump 64 has a discharge pipe 67 connecting with thecontrol board`54 whereon are mounted a pressure control valve 68 and apressure gauge 69; between, lines 67 and 60 onvthe control board is abypass valve and connection 7 0; from the control board the line67'extends to the branch connection 71; from the latter extends a line72 and valve 72 connecting to the heat exchanger 11; the heat exchangerhas a corresponding outlet pipe 73 connecting to the pipe 74; from thebranch connection 71 extends a line 74 and valve 74 to the inlet side ofthe economizer coil 75 in furnace 1; the outlet side of coil 75 connectswith the pyrometer fitting 76 which acts as a branch fitting; one branch77 and valve 77 connects with the mixing chamber 8 and the other branch78 with its valve 78 connects to the header 15. The furnace 1 is littedwith a burner 79 and also an auxiliary burner 80, also a smoke stack 81;the coils 6 are fitted with pyrometer fittings 82 and 82'; 83 is the oilsupply tank and 84 is the make-up oil or fresh supply tank.

There are a number of instances where I show on the drawing fittings,valves, etc., which I have not numbered, as they are selfevident incharacter and anyone familiar with the art to which this inventionrelates will readily understand their significance and function.

Having now described my apparatus, I will describe its operation:

The pump 58 is started and takes suction on the supply tank 83, throughline 59 and discharges the oil through line 60 to the control board 54and through the pressure regulating valve 61 in line 60, from whence theoil passes to the preheating coil 2, then to the coil 4 by way of pipe3, then into the final heating and cracking coil 6 by way of pipe 5;from the cracking coils 6 the oil passes to the carbon precipitating andmixing Chambcr 8 by way of pipe 7. At a point in the mixing chamber nearthe pipe 7 is an entering pipe 77 connected to the economizer coil 75which is located in the terminal passes of the furnace 1; this coil mayhave a supply of additional heat furnished by the burner 80, if sodesired, in order to increase its capaclty and cracking effect. The coil75 may be supplied with o1l through the pipe 74 which connects with thevalve 68 on the control board 54; in the line 74 is a bypass 72connecting with the heat exchanger 11 designed to supply heat to the oilgoing to the economizer coil and extracting heat from the outgoing oilfrom the carbon precipitating and mixing chamber 8; from the valve 68 onthe control board extends a pipe 67 connected to the pump 64 which istaking suction on the supply tank and will be pumping for the time beingthe same oil as is being pumped by the. The oil in the two distinctc1rpump 58. cuits is heated by the heat supplied by the burner 7 9 and,if desired, the burner 80 may also supply additional heat. The oil inthe primary cracking coils 2, also coils 4 and 46, will be heated to anactive cracking tempefiature, the quantity of oil pumped and the supplyof heat being so regulated as to bring about this result. Now the oilpassing through the secondary or economizercoil is so regulated, as toquantity, as to bring its temperature to a point approximating itscracking point more or less- (as previously stated, the quantity pumpedmay be increased by employing additional heat from the burner 80, carebeing taken to so regulate the heat as to maintain a substantial heatdifferential between the two oils as they leave the heating coils) thetwo streams of oil are now introduced into the mixing chamber 8 wherethe oil of lower temperature is instantaneously increased in temperaturefrom an incipient cracking temperature to one of active cracking, thecracking action being highly accelerated by the rapidit of the increaseof heat. This reaction an the two heating steps are carried on under ahigh pressure sulicient to prevent material vaporization, the admixtureof the two being in a liquid condition. The mixture of oils then passesthrough the carbon precipitating chamber or mixingI chamber (where anyfree carbon is precipitated) into the heat exchanger/11, thence to thebypass tra 13 which is in open communication throug the line 51, cooler52 and line 53 to the terminal pressure reducing valve 55'; the pressurebeing observed by the gauge 55; from the valve e 55' extends a line 56to the slop tank or the cracked oil tank. From the bypass trap 13 thereis connected an outlet pipe 14 and pressure reducing valve 14' locatedtherein and which connects into the header 15, which in turn connectsinto the fractionatin tower 16. The header 15 is simply a manifold toreceive similar connections to 14 from other units in a battery ofcracking units and where one tower will take care of the vapors of abattery of units.

In operating in this manner, I prefer to use a terminal pressure of onethousand pounds, more or less, with an inlet pressure suliicientlyhigher to overcome the friction of the pipe, bends, etc., and which maybe as high as one thousand five hundred pounds, or

more. V

The pump 64 may take suction on the fresh supply tank 84, through pipeand valve 65', if it is desired to replenish the system with fresh oil,or the fresh oil may be introduced into the system by putting it intotank 83 and which may be done if the makeup oil is a distillate or is aclean oil that would not cause fouling of the primary coils; whereas, ifthe make-up oil is a heavy grade, such as fuel or crude oil which mightcause fouling of the tubes of the primary coils, then the make-up oilshould be stored in tank 84, so that pump 64 may introduce it into thesystem through the economizer coil where danger of carbonizing orfouling is a minimum. If, for instance, fuel or crude oil wereintroduced into the system by putting it into the supply tank 83, thenthe pump 58 would discharge the heavy oil through the primary crackingcoils which would rapidly foul and cause more or less trouble, whereasif the pump 64 handles the make-up or fresh supply oil it can be soregulated that the heating effect in the economizer coil will be suchthat nothing more than incipient cracking will take place therein, theactive cracking taking place in the mixing chamber or carbonprecipitating chamber, where carbon can be readily cleaned out orpurged. By this arrangement, the coils will remain clean and practicallyfree of carbon.

The economizer coil also has a bypass connection 78 in which is apressure reducing valve 78'; this line is connected to the header 15 andis used as a bypass in case of trouble to line 77 or if it is desired tovaporize a stock in the fractionating towers without cracking it in themixing chamber.

The pump 58 may be operated to furnish the ordinary or economizer coilwith its supply of oil and at the same time furnish the primary coilswith their supply of oil-(by operating in this way both coils will besupplied with the same grade of oil). The two coils will function in anidentical manner as if each had an individual pump, the regulation ofthe supply to each coil being controlled by suitably situated valves.For instance, pump 58 can take suction on the supply tank 83 anddischarge through line 60 to the control board 54 and by having Valve 61open, the primary coils 2, 4 and 6 may be supplied and also valve may beopen through which the secondary or economizer coils may be suppliedwith oil.

The same arrangement also applies to pump 64 which may take suction onthe supply tank 83 and also on the fresh supply tank 84 and dischargethrough line 67 to the control board 54 and with valve 68 open, togetherwith valve 7 2' or 74', the secondary or economizer coils will besupplied with oil, and, if valve 70 is simultaneously opened, theprimary coils will be supplied with oilthe quantities to each coil beingcontrolled by valve 70 for the primary coils and valve 72' or 74 for thesecondary coils.

When I wish to blow down the system, I shut o the supply of oil to pump58 and open the suction lnto the water tank, the pumpthen dischargingwater to the coils and driving the oil ahead of it; the valve 14' beingclosed, the oil and water discharges through the bypass trap 13, throughpipe 51, cooler 52, pipe 53, pressure reducing valve 55' and line 56 tothe slop tank, or if the oil is coming clean it is run into the crackedoil tank. When the oil is displacedin the tubes, then the blow-oil'connection 9 on the chamber.8 is opened and the carbon or carbonaceousmaterial is blown out of the tubes and carbon precipitating chamber.

To simultaneously blow down the economizer coil with the primary coils,I close valve 68 on the control board and open valve 70, therebyadmitting water from the pipe 60 and pump 58 into the pipe 67 andthrough the valves 72' and 74' to the economizer coil which willdischarge into the carbon precipitating chamber through pipe 77 and bedischarged through the blow-olf 9.

It is essential when discharging pump 64 pressure will be a thousandpounds, more or less. When operating to discharge into the header 15,comparatively low pressure can be employed. When the oil and vapordischarge from the header 15, they enter the tower 16, wherein they arefractionated; from tower 16 the vapors pass to tower 21 where they arefurther fractionated. Tower 16 will separate in compartment 17 a heavyresidue which is cooled and run to the residue tank. Tower 16 will alsoseparate in compartment 18 a cycling stock which may be withdrawnthrough pipe 34 and valve 34 to the cooler and pipe 37 to the supplytank 83 to be rerun. Tower 16 will also separate in compartment 19 anintermediate naphtha stock which may be withdrawn through pipe 35, valve35', through the cooler and pipe 38, to the intermediate naphtha tank.The intermediate naphtha may be sprayed into the compartment 18 throughspray pipe 39 by opening valve 36 and closing valves 35 and 47, or itmay be run to the lower part of the tower 21 through valve 47, havingvalves 35 and 36 closed.

The residue from tower 21 is a. heavy naphtha and may be drawn offthrough connection 29, thence to the cooler, look box 30, pipe 32, tothe heavy naphtha tank, or it may be run to the supply tank 83througlrline 31.

The pump 44 is arranged to take suction on the intermediate naphtha andalso on the heavy naphtha tanks, so that these stocks may be sprayedinto the various tower compartments as a scrubbingr and condensing meiumand to be revaporized and again fractionated, or they may be used as acondensing medium in the analyzer 24, the oil entering through pipe 45and valve 45 and discharging through pipe 46 and valve 46 through thecooler, then back to the original tank from which it came; or by closingvalve 46 and opening 48 the oil may be discharged into the lower portionof tower 21 to be refractionated.

The final vapors leaving tower 21, through the analyzer 24, can be madea light naphtha containing a large percentage of gasoline, or it can bemade a crude test gasoline not requiring further distillation to refineit.

What I claim as new and desire to obtain by Letters Patent is:

1. The process of cracking hydrocarbons in substantially the liquidphase comprising heating a primary supply of hydrocarbons in a heatingfurnace to a degree sufficient to crack them, then discharging them intoa carbon precipitating and reaction chamber and maintaining throughoutthe cracking system a pressure sufficient to prevent materialvaporization of the hydrocarbons, and simultaneously heating in atubular heating element a secondary supply of hydrocarbons in theterminal combustion spaces of the primary heating furnace andmaintaining thereon, to the point of pressure release and discharge,sufficient pressure to prevent material vaporization thereof.

2. The process of cracking hydrocarbons in substantially the liquidphase comprising heating a primary supply of hydrocarbons in a heatingfurnace to a degree sufficient to crack them, then discharging them intoa carbon precipitating and reaction chamber and maintaining throughoutthe cracking system a pressure sufficient to prevent materialvaporization of the hydrocarbons, and simultaneously heating in atubular heating element a secondary supply of hydrocarbons in theterminal combustion spaces of the primary heating furnace andmaintaining thereon sufficient pressure to prevent matel rialvaporization thereof, then discharging the heated hydrocarbons of theprimary and secondary supplies into a fractionating apparatus, thencondensing and separating the various fractions, and returning to thecracking system those fractions suitable for recracking.

3. The pro-cess of cracking hydrocarbons in substantially the liquidphase comprising separately heating in a single furnace two supplies ofhydrocarbons-first heating a primary regulated supply in a continuousheating element in a single pass through the furnace to a temperaturesufficient to actively crack them and, secondly, hea-ting a secondaryregulated supply in a single pass through a continuous heating element,so disposed in said furnace whereby its heating effect is obtained fromwaste gases of the primary heat ing effect, and so regulating thesecondary supply that the degree of heating obtained therebyapproximates its incipient cracking point, then discharging the primaryand secondary supplies into a mixing chamber whereby the temperature ofthe secondary supply is suddenly increased to an active cracking degreeand maintaining on the primary and secondary heating elements and mixingchamber a pressure sufficient to prevent material vaporization thereofand maintaining said pressure to the point of pressure release anddischarge.

4. The process of cracking hydrocarbons in substantially the liquidphase comprising separately heating in a single furnace two supplies ofhydrocarbons-rst heating a primary regulated supply in a continuousheating element in a single pass through the furnace to a temperaturesufficient to actively crack them, and, secondly, heating a secondaryregulated supply in a. single pass through a continuous heating element,so disposed in said furnace whereby its heating effect is obtained fromwaste gases of the primary heating effect, and so regulating thesecondary supply that the degree of heating obtained therebyapproximates its incipient cracking point, then discharging the primaryand secondary supplies into a mixing chamber whereby the temperature ofthe secondary supply is suddenly increased to an active cracking degreeand maintaining on the primary and secondary heating elements and mixingclianiber a pressure sufficient to prevent material vaporization thereofand maintaining said pressure to the point of pressure release anddischarge then discharging the h ot mixture of hydrocarbons into afractionating apparatus wherein the various fractions are separated andthe hydrocarbons suitable for recracking are returned to the crackingsystem for further cracking.

5. The process of cracking hydrocarbons in substantially the liquidphase comprising heating a primary supply of hydrocarbons in a heatingfurnace to a degree sufficient to crack them, then discharging them intoa carbon precipitating and reaction chamber and maintaining throughoutthe cracking system a pressure sufficient to prevent materialvaporization of the hydrocarbons, and simultaneous'j.; heating asecondar)v supplyof hydrocarbons in the terminal combustion spaces ofthe primary heating furnace to a temperature suiiicient to reduce theviscosity of the residues resulting from the vaporization andfractionation of the said secondary supply of hydrocarbons andmaintaining thereon a pressure suiiicient to prevent materialvaporization thereof and maintaining said pressure to the point ofpressure release and discharge.

6. The process of cracking hydrocarbons in substantially the liquidphase comprising heating a primary supply of hydrocarbons in a heatingfurnace to a degree suicient to crack them` then discharging them into acarbon precipitating and reaction chamber and maintaining throughout thecracking system a. pressure sufficient to prevent material vaporizationof the hydrocarbons, and simultaneously heating a secondary supply ofhydrocarbons in the terminal combustion spaces of the primary heatingfurnace to a temperature suflicient to reduce the viscosity vof theresidues resulting from the vaporization and fractionation of the saidsecondary supply of hydrocarbons and maintaining thereon a pressuresuiiicient to prevent material vaporization thereof to the point ofpressure release and discharge, then discharging the primary andsecondary supplies of .hydrocarbons into a fractionating apparatus, andreturning to the cracking system those fractions suitable forrecracking.

7. The process of cracking hydrocarbons in the liquid phase comprisingheating a primary supply of hydrocarbons to a temperature sufficient tocrack them, then discharging them into a mixing chamber wherein isintroduced a secondary supply ofhydrocarbons heated in the same furnaceto a degree approximating its incipient cracking point, the mixture ofhydrocarbons supplying sufficient signature.

JOHN C. BLACK.

